DESCRIPTION: (Adapted from the applicant's abstract.) The long term goal of the research is to develop a noninvasive, objective method for evaluating color vision. The method of study is based on the observation that (in addition to its responses to changes in stimulus luminance), the pupil of the eye produces a transient constriction to isoluminant chromatic stimulus exchanges. The pupil constricts, for example, if a red spot is replaced by an isoluminant green spot and vice versa. The specific aims are to set up a laboratory for studying these transient pupillary responses in adult observers, to study the response evoked by stimuli of various chromaticities, to investigate the relationship between response magnitude and such factors as stimulus size and retinal eccentricity, to test whether the spatial pattern within the stimulus field affects the response, to determine how chromatic and luminance components of the pupillary response combine, and to determine the contribution of rods to the transient pupillary response. Research of such pupillary responses may lead to new alternatives in the clinical evaluation of visual abnormalities, in the evaluation of the visual status of noncommunicative or cognitive-impaired subjects, in the study of the visual development of infants or in the psychophysical study of animal vision.